Abstract
The deposition/dissolution mechanism of MnO(2) with two-electron transfer is promising for high-energy aqueous energy storage. However, this reaction is severely limited by the kinetically unfavorable dissolution step, a challenge that is greatly exacerbated as the deposit thickens. Herein, by refining NH(4) (+)-mediated interface chemistry, we achieve the precise configuration of MnO(2) with controlled hydroxylation, which guides the reversible MnO(2)/Mn(2+) conversion under high-mass-loading conditions. The partially hydroxylated surface further creates a kinetically favorable microenvironment for NH(4) (+) storage, ultimately leading to energetic dual-pathway storage behaviors. This enables a remarkable areal capacitance of 13.8 F cm(-2) and sound cycling stability over 6000 cycles under high-mass-loading conditions (27.1 mg cm(-2)). Theoretical calculations reveal that the controlled partial hydroxylation of MnO(2) promotes electronic conduction and lowers the adsorption energy of NH(4) (+), outperforming both highly hydroxylated and pure MnO(2). The adsorbed NH(4) (+) delivers intimate interfacial electronic interaction with partially hydroxylated MnO(2) to trigger local charge redistribution, substantially lowering the MnO(2)/Mn(2+) conversion energy barrier of the nonspontaneous rate-determining step at the NH(4) (+)-proximal site. Our findings highlight the significance of the interfacial microenvironment governing the collaborative dual-pathway storage chemistry, which provides guidance for boosting high-mass-loading energy storage.